Nuclear magnetic resonance (NMR) techniques will be used to study molecular dynamics in liquid crystals and in membrane systems. Diffusion in oriented lecithin/water bilayers will be measured using pulsed NMR techniques. The lateral diffusion of the lipid molecules and the diffusion of the water both parallel and perpendicular to the bilayers will be measured as a function of temperature and of lipid concentration. Diffusion in mixed lipid/water systems will also be investigated. Membrane phase transitions will be investigated using proton enhanced carbon-13 NMR. A spectrometer is being completed and the studied will focus on molecular configuration changes which accompany phase transitions in bilayers. NMR relaxation mechanisms in nematic liquid crystals will be studied using isotopic dilution techniques. By measuring proton relaxation in partially deuterated p-azoxyanisole (PAA) as a function of dilution in perdeuterated PAA the inter- and intramolecular contributions to Tl can be determined. These contributions will be obtained as a function of frequency and temperature, then compared with theoretical predictions. BIBLIOGRAPHIC REFERENCES: "Deuteron Relaxation in Liquid Crystals: Di-n-alkoxyazoxybenzenes, n equals 1,7 " R.D. Orwoll, C.G. Wade and B.M. Fung, Journal of Chemical Physics 63, 986 (1975). "Spin Lattice Relaxation in an Homologous Series of C18 Esters of Cholesterol." R.C. Matthews and C.G. Wade, Journal of Magnetic Resonance (July 1975 issue).